There are a lot of types of jamming attacks. The object is to jam the system from providing services in a short term, in which the power exhaustion denial-of-service attack is a very destructive attack. Because the lifespan of sensor nodes in a wireless network is limited by the power consumption of the battery, when the power is exhausted, the sensor nodes can not operate. For example, the attacker can fake a message asking the sensors nodes continuously retransmitting messages to exhaust its energy. In the wireless sensor network, the data transmission is the most power-consuming.
The jamming attack can be initiated on the link layer or the physical layer. The jamming attack on the link layer employs a jammer to interfere the communication among the sensor nodes. This kind of jamming attack actually employs some weaknesses of the link layer protocol. The jamming attack on the physical layer employs the radio frequency to interfere the opened wireless environment. Because the sensor node only has a single channel, the jammer will seize the usage right of the channel, the sensor node could not transmit the sensing message to the base station.
However, for the conventional jamming attack, after the attacker distributing the mobile jammer initiating the jamming attack to the wireless sensor network, the location of the attacker initiating the jamming attack is the location of distribution. At this time, the jammed sensor node is possibly the unimportant node in a role among the wireless sensors, so that the affected range to the entire wireless sensor network is not so large.
Based on the conventional jamming attack, the defending scheme can be classified into an active mode and a passive mode. The active mode can detect the occurred attack and find out the jammed areas. However, this kind of defending scheme will increase the overhead of transmission and operation of the sensor node, and will easily exhaust the lifespan of the sensor node.
The passive mode employs modifying the MAC layer protocol or reducing the packet transmission frequency to achieve the purpose of power saving. S-MAC (Sensor MAC) and T-MAC (Timeout MAC) are the associated communication protocol. S-MAC employs the periodical sleep mode to make the wireless sensor enter the sleep state to achieve the power-saving effect, but entering the sleep state will stop the data transmission and cause the sleep delay. T-MAC reduces the working period to achieve the purpose of power-saving, but it did not consider the data transmission performance and the problem of sleep delay. Furthermore, except of the above-mentioned problems, both communication protocols, S-MAC and T-MAC have a common defect under the jamming attack, which is that both of the communication protocols will be destroyed by only jamming the data packets and the control packets.
To this end, the applicant has developed the “denial-of-service attacks in a wireless sensor network and the defending scheme thereof” as the present application, so as to improve the defects in the prior art.